This invention relates to miniature snap-action switches, often known as micro-switches. Such switches usually employ an actuating member such as a button, which requires a low force to actuate it. Indeed, it is usually considered desirable to keep the actuating force as low as possible, consistent with adequate contact pressures being obtained within the switch. However, in some situations the restoring force produced by the switch itself is employed to return to its starting position the external element that acts on the switch; in such a case a high actuating force is desirable.
It would be possible to achieve this by increasing the strength of the snap action spring of the switch but, because it is a highly stressed component, this may reduce the mechanical life of the switch to an unacceptable level.
The introduction of compression springs under the end of the carrier, below the button, is a known method of dealing with this problem, but has several disadvantages. Because of its finite diameter, a compression spring acting against the carrier can exert a moment of force which changes the operating characteristics of the snap-action. To accommodate a compression spring of suitable rate, a deep, clear, space is required directly under the point of contact of the button and carrier. This is not available in most switches of this type due to the obstruction of mandatory standard mounting holes, one of which passes through the switch in this area. Compression springs, because of their open coils, are difficult to assemble by automatic means.